Internal combustion engines are conventionally powered by the introduction of a fuel, such as gasoline or diesel, and air into a combustion chamber. Typically, the combustion chamber is fashioned as a cylinder in which a piston is slidably confined. A spark ignites the fuel and air mixture, causing an explosion. The expanding gases resulting from the explosion act on and forcefully move the piston in the cylinder. The piston is connected through a connecting rod to a rotatable crankshaft, which may be connected to wheels and other devices to perform useful work.
Valves are used to control the injection of air and fuel into the combustion chamber and to allow the ignited, expanded gas to exit the combustion chamber. The timing for opening and closing the valves is controlled by a camshaft, which in turn is synchronized to the crankshaft by a chain, belt, or gear.
A valvetrain typically includes the valves, valve springs (such as metal coil springs) that bias the valve into a closed position, rocker arms that act upon the valves to move the valves against the valve spring bias and to open the valves, push rods that actuate the rocker arms, and lifters that ride on the camshaft and act on the ends of the push rods.
The valvetrain components, especially metal valve springs, usually become very hot. Because the valve springs often cycle through compression and extension many hundreds, if not thousands, of times per second during the operation of an internal combustion engine, the metal in the valve springs becomes hot due to the flexion of the metal. The exhaust valve springs are especially prone to becoming very hot because the exhaust valve opens near the end of the combustion cycle, while there is still some combustion pressure in the combustion chamber, and the hot combustion gases exit the combustion chamber, around the valve head and valve stem, and pass through the exhaust port. Heat travels up the valve stem and is transferred to the exhaust valve spring.
Although spraying oil or another lubricant onto the springs has been used in an attempt to cool the valve springs, the temperature of the oil, particularly oil used in an engine under load, can reach three hundred degrees or more, which results in an ineffective attempt to cool the valve springs with hot oil.
Reducing the temperature of the valvetrain components, such as valve springs, will increase valvetrain longevity, decrease the chance of engine-damaging detonation, and increase operating efficiency of the engine.